Tinted, high Dk ophthalmic molding and a method for making same

ABSTRACT

The invention relates to ophthalmic molding formulations and to tinted, high Dk ophthalmic moldings. This invention also relates to a method for making a tinted ophthalmic molding. The method comprises: (a) providing a polymer precursor having cross-linkable or polymerizable groups; (b) providing a pigment dispersion comprising an inorganic or organic pigment and a dispersing agent; (c) mixing the pigment dispersion with the polymer precursor to form a tinted prepolymer mixture; (d) dispensing the tinted prepolymer mixture into a mold; and (e) forming a tinted ophthalmic molding from the tinted prepolymer mixture, the molding comprising a polymer matrix having the pigment entrapped therein. With this method, tinted ophthalmic moldings, particularly edge-to-edge soft, tinted contact lenses having improved properties, are prepared with an improved efficiency.

This application claims the benefit under 35 U.S.C. §119(e) of U.S.provisional application No. 60/259,957 filed Jan. 5, 2001.

FIELD OF THE INVENTION

This invention relates broadly to optic and ophthalmic arts. Moreparticularly, this invention relates to tinted polymeric materials,tinted ophthalmic moldings and methods useful in making tintedophthalmic moldings. Still more particularly, this invention relates tocompositions and methods for making high Dk, visibility (“full body” or“edge-to-edge”) tinted contact lenses.

BACKGROUND OF THE INVENTION

1. High Dk Ophthalmic Moldings

In the field of ophthalmic moldings, and in particular in the field ofcontact lenses, a biocompatible lens may be generally defined as onewhich will not substantially damage the surrounding ocular tissue andocular fluid during the time period of contact. The phrase“ophthalmically compatible” more appropriately describes thebiocompatibility requirements of ophthalmic lenses.

One ophthalmic compatibility requirement for contact lenses is that thelens must allow oxygen to reach the cornea in an amount which issufficient for long-term corneal health. The contact lens must allowoxygen from the surrounding air to reach the cornea because the corneadoes not receive oxygen from the blood supply like other tissue. Ifsufficient oxygen does not reach the cornea, corneal swelling occurs.Extended periods of oxygen deprivation causes the undesirable growth ofblood vessels in the cornea. “Soft” contact lenses conform closely tothe shape of the eye, so oxygen cannot easily circumvent the lens. Thus,soft contact lenses must allow oxygen to diffuse through the lens toreach the cornea.

While there exist rigid gas permeable (“RGP”) contact lenses which havehigh oxygen permeability and which move on the eye, RGP lenses aretypically quite uncomfortable for the consumer. Thus, soft contactlenses are preferred by many consumers because of comfort. Moreover, acontact lens which may be continuously worn for a period of a day ormore (including wear during periods of sleeping) requires comfort levelswhich exclude RGP lenses as popular extended-wear candidates.

In order to balance the ophthalmic compatibility and consumer comfortrequirements in designing a daily wear soft contact lens, polymers andcopolymers of 2-hydroxyethyl methacrylate (HEMA) were developed. Thesehydrophilic polymers move well on the eye and provide sufficient oxygenpermeability for daily wear. Certain soft contact lenses have beenapproved by the FDA for extended wear periods of up to about 6 nights ofovernight wear and seven days of daily wear. However, the consumercannot safely and comfortably wear these poly(HEMA) lenses for extendedperiods of seven days or more, because the oxygen permeability isinsufficient. True extended wear (i.e., seven days or more) of theselenses may result, at a minimum, in corneal swelling and development ofsurface blood vessels in the cornea.

In order to improve oxygen permeability, polymers containing siliconegroups were developed. A variety of siloxane-containing polymers havebeen disclosed as having high oxygen permeability (high Dk). Forexample, see U.S. Pat. Nos. 3,228,741; 3,341,490; 3,996,187; and3,996,189.

2. Tinted Ophthalmic Moldings

A number of dyes have been incorporated into ophthalmic moldings, suchas contact lenses, for a variety of reasons. Two popular type of dyesinclude ultraviolet (UV) light absorbing agents. One common reason forincorporating dyes into contact lenses is to produce a lens that changesthe apparent perceived color of the wearer's iris. Another reason to dyea lens is to enable the user to easily locate a lens in a clear solutionwithin a lens storage, disinfecting or cleaning container. Dyeing a lensfor this purpose is for “visibility tinting” the lens.

Visibility tinting may be accomplished by applying a dye to a portion ofthe surface or by applying the dye to the full front surface of thelens. Alternatively, the tint may be incorporated into the full body ofthe polymer matrix of the lens. There have been a number of patents andpublished patent applications relating to tinting contact lenses ormaking contact lenses that change the wearer's iris color. However,these processes are not yet totally satisfactory, for example, withrespect to the types of lens materials used to tint, the productionefficiency, and/or the quality of the products obtained.

Thus, there remains a need for an ophthalmically compatible, visibilitytinted transparent polymeric lens material which is suited to short andextended periods of continuous contact with ocular tissue and tearfluid. In addition, there is still a need for a method of making animproved visibility tinted, i.e., a full body, edge-to-edge tintedcontact lens with an improved efficiency by minimizing in-lineproduction steps. Also, there remains a need for a method for tinting orcoloring a lens that does not require the use of reactive dyes andassociated wet processing necessary to remove unbound dye, activator andreaction by-products.

Moreover, there is a need for tinted ophthalmic lenses with improvedproperties, for example, with respect to high oxygen permeability,increased mechanical strength, reduced leaching or migration of dye orpigment out of the lens material, and color retention during exposure toUV light during photopolymerization.

SUMMARY OF THE INVENTION

In accordance with the purpose of this invention, as embodied andbroadly described herein, this invention, in one aspect relates to asoft, tinted ophthalmic molding comprising a polymer matrix having ahigh oxygen permeability and incorporated therein a pigment.

In another aspect, this invention relates to a soft, tinted ophthalmiclens comprising the reaction product of (i) a cross-linkable orpolymerizable material capable of forming a polymer or copolymer havinga high oxygen permeability; and (ii) a pigment dispersion comprising apigment and a dispersing agent.

In yet another aspect, this invention relates to a composition formaking a soft, tinted ophthalmic lens comprising (i) a cross-linkable orpolymerizable material capable of forming a polymer or copolymer havinga high oxygen permeability; and (ii) a pigment dispersion comprising apigment and a dispersing agent.

In another aspect, this invention relates to a method for making a soft,tinted ophthalmic molding comprising: (a) providing a polymer precursorcapable of forming a polymer or copolymer having high oxygenpermeability; (b) providing a pigment dispersion comprising a pigmentand a dispersing agent; (c) mixing the pigment dispersion and thepolymer precursor to form a tinted prepolymer mixture; (d) dispensingthe tinted prepolymer mixture into a mold; and (e) cross-linking orpolymerizing the tinted prepolymer mixture in the mold to form a soft,tinted ophthalmic molding having high oxygen permeability comprising apolymer matrix and the pigment entrapped therein.

Additional advantages of the invention will be set forth in part in thedetailed description, which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theadvantages of the invention will be realized and attained by means ofthe elements and combinations particularly pointed out in the appendedclaims. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory of preferred embodiments of the invention, and are notrestrictive of the invention, as claimed.

DETAILED DESCRIPTION OF THE INVENTION

The present invention may be understood more readily by reference to thefollowing detailed description of the invention and the examplesprovided therein. It is to be understood that this invention is notlimited to the specific methods and conditions and parameters described,as specific methods and/or method conditions and parameters forprocessing polymers and polymer formulations as such may, of course,vary. It is also understood that the terminology used herein is used forthe purpose of describing particular embodiments only and is notintended to be limiting. It must also be noted that, as used in thespecification including the appended claims, the singular forms “a,”“an,” and “the” include plural references unless the context clearlydictates otherwise.

Ranges may be expressed herein as from “about” or “approximately” oneparticular value and/or to “about” or “approximately” another particularvalue. When such a range is expressed, another embodiment includes fromthe one particular value and/or to the other particular value.Similarly, when values are expressed as approximations, by use of theantecedent “about,” it will be understood that the particular valueforms another embodiment.

One embodiment of the present invention is a method of tinting anophthalmic molding or lens comprising mixing a miscible, liquid pigmentdispersion or colorant with a liquid, polymerizable lens material orformulation.

Another embodiment of this invention relates to a soft, tintedophthalmically compatible, transparent lens suited for continuouscontact with ocular tissue and tear fluids. A particularly preferredembodiment of the invention is a soft, tinted vision correction lenssuited for safe and comfortable wear. In order to properly describe theinvention and to delineate the metes and bounds of the claims, a set ofbasic terms will be defined at the outset.

I. Definition of Terms

An “ophthalmic molding”, as used herein, refers to moldings or lenseswhich are placed in intimate contact with the eye or tear fluid, such ascontact lenses for vision correction (e.g., spherical, toric, bifocal),contact lenses for modification of eye color, ophthalmic drug deliverydevices, ocular tissue protective devices (e.g., ophthalmic healingpromoting lenses), and the like. A particularly preferred ophthalmicmolding is a tinted contact lens, especially a contact lens for visioncorrection.

A “polymer precursor” and “prepolymer,” as used herein, refer to across-linkable or polymerizable material. Preferably, the polymerprecursor is hydrophobic and more preferably is a silicone-containingmacromer or monomer.

A “polymerizable material which is capable of polymerizing to form apolymer having a high oxygen permeability,” as used herein, refers tomonomers, oligomers, macromers, and the like, and mixtures thereof,which are capable of polymerizing with like or unlike polymerizablematerials to form a polymer which displays a relatively high rate ofoxygen diffusion therethrough. For convenience of reference, thesematerials will be referred to herein as “oxyperm polymerizablematerials” and the resultant polymers will be referred to herein as“oxyperm polymers”.

The “oxygen transmissibility” of a lens, as used herein, is the rate atwhich oxygen will pass through an ophthalmic lens. Oxygentransmissibility, Dk/t, is conventionally expressed in units ofbarrers/mm, where t is the average thickness of the material [in unitsof mm] over the area being measured and “barrer” is defined as:

((cm³ oxygen)(mm)/(cm²)(sec)(mm Hg))×10⁻⁹

The “oxygen permeability”, Dk, of a lens material does not depend onlens thickness. Oxygen permeability is the rate at which oxygen willpass through a material. Oxygen permeability is conventionally expressedin units of barrers, where “barrer” is defined as:

((cm³ oxygen)(mm)/(cm²)(sec)(mm Hg))×10⁻¹⁰

These are the units commonly used in the art. Thus, in order to beconsistent with the use in the art, the unit “barrer” will have themeanings as defined above. For example, a lens having a Dk of 90 barrers(“oxygen permeability barrers”) and a thickness of 90 microns (0.090 mm)would have a Dk/t of 100 barrers/mm (“oxygen transmissibilitybarrers”/mm).

A “polymerizable material which is capable of polymerizing to form apolymer having a high ion permeability” as used herein, refers tomonomers, oligomers, macromers, and the like, and/or mixtures thereof,which are capable of polymerizing with like or unlike polymerizablematerials to form a polymer which displays a relatively high rate of ionor water permeation therethrough. For convenience of reference, thesematerials will be referred to herein as “ionoperm polymerizablematerials” and the resultant polymers will be referred to herein as“ionoperm polymers”.

A “macromer”, as used herein, refers to a polymerizable material whichhas a molecular weight of at least about 800 grams/mol. The term“macromer”, as used herein, also encompasses oligomers.

A “monomer”, as used herein, refers to a polymerizable material whichhas a molecular weight of less than about 800 grams/mol.

“Pigment(s), as used herein, shall mean any substance that imparts colorto another material or mixture. Pigment is sometimes used synonymouslywith “colorant.” Pigments are usually dry powders and may be inorganicor organic.

“Dispersion or dispersed,” as used herein, refers to a variety of levelsor degrees of separation of pigment particles in a dispersing agent.

“Ophthalmically compatible”, as used herein, refers to a material orsurface of a material which may be in intimate contact with the ocularenvironment for an extended period of time without significantlydamaging the ocular environment and without significant user discomfort.Thus, an ophthalmically compatible contact lens will not producesignificant corneal swelling, will adequately move on the eye withblinking to promote adequate tear exchange, will not have substantialamounts of lipid adsorption, and will not cause substantial wearerdiscomfort during the prescribed period of wear.

“Ocular environment”, as used herein, refers to ocular fluids (e.g.,tear fluid) and ocular tissue (e.g., the cornea) which may come intointimate contact with a contact lens used for vision correction, drugdelivery, wound healing, eye color modification, or other ophthalmicapplications.

The “outer surface” of a lens, as used herein, refers to the surface ofthe lens which faces away from the eye during wear. The outer surface,which is typically substantially convex, may also be referred to as thefront curve of the lens. The “inner surface” of a lens, as used herein,refers to the surface of the lens which faces towards the eye duringwear. The inner surface, which is typically substantially concave, mayalso be referred to as the base curve of the lens.

“TRIS”, as used herein, refers to3-methacryloxypropyltris(trimethylsiloxy) silane. The term “TRIS” alsoincludes dimers, trimers, and the like of3-methacryloxypropyltris(trimethylsiloxy) silane.

“Molecular weight” of a polymeric material (including monomeric ormacromeric materials), as used herein, refers to the number-averagemolecular weight unless otherwise specifically noted or unless testingconditions indicate otherwise.

II. Polymer Precursor and Polymeric Materials

In a preferred embodiment, the polymer precursor is a prepolymer, e.g.,macromer, having a number average molecular weight of at least about300. The prepolymer has more preferably a number average molecularweight of about 300 to about 30,000, and even more preferably from about500 to about 20,000. Most preferred, the prepolymer has a number averagemolecular weight of about 1,000 to about 10,000.

The prepolymer used with this invention includes polymerizable orcross-linkable groups. “Cross-linkable groups” denotes customarycross-linkable groups well known to a person skilled in the art, such asfor example, photo cross-linkable or thermally cross-linkable groups.Cross-linkable groups such as those already proposed for contact lensmaterials are suitable. Those include, but are not limited to groupscomprising carbon-carbon double bonds. To demonstrate the large varietyof suitable cross-linkable groups, there are mentioned here, merely byway of example, the following cross-linking mechanisms: radicalpolymerization, 2+2 cyclo addition, Diels Alder reaction, ROMP (ringopening metathesis polymerization), vulcanization, cationiccross-linking and epoxy hardening.

The polymerizable or cross-linkable materials useful with the presentinvention include a wide variety of materials known in the art.Preferred polymeric materials are those which are transparent and can beused in biocompatible, especially ophthalmically compatibleapplications.

A particularly preferred class of prepolymer and polymeric materialsuseful for this invention are those disclosed in U.S. Pat. No.5,760,100, issued to Nicolson et al., the entirety of which is herebyincorporated by reference.

A. Oxyperm Polymerizable Materials

Oxyperm polymerizable materials include a wide range of materials whichmay be polymerized to form a polymer displaying a relatively high oxygendiffusion rate therethrough. In addition, these materials must berelatively ophthalmically compatible. These oxyperm polymerizablematerials include, without limitation thereto, siloxane-containingmacromers and monomers, fluorine-containing macromers and monomers, andcarbon-carbon triple bond-containing macromers and monomers. The oxypermmacromer or monomer may also contain hydrophilic groups.

Preferred oxyperm polymers are those formed from a siloxane-containingmacromer. Macromers having dialkyl siloxane groups, especially dimethylsiloxanes, are particularly preferred. These macromers are broadlyreferred to as poly(dimethyl siloxanes) (also, PDMS). Thesiloxane-containing macromer may also include hydrophilic groups.Examples of suitable siloxane-containing macromers include, withoutlimitation thereto, those disclosed and described in U.S. Pat. No.5,760,100 issued to Nicolson et al., which is herein incorporated byreference in its entirety.

The oxygen transmissibility (Dk/t) of the lens is preferably at least 60barrers/mm, more preferably at least 65 barrers/mm, and most preferablyat least 70-80 barrers/mm. The lens center thickness is typically morethan about 30 microns, preferably about 30 to about 200 microns, morepreferably about 40 to about 150 microns, even more preferably about 50to about 120 microns, and most preferably about 60 to about 100 microns.

The oxygen transmissibility of an extended-wear lens, for example, fromthe outer surface to the inner surface must be sufficient to prevent anysubstantial corneal swelling during the period of extended wear. It isknown that the cornea swells approximately 3% to 4% during overnightperiods of sleep when the eyelids are closed, as a result of oxygendeprivation. It is also known that wearing a typical contact lens, suchas ACUVUE (Johnson & Johnson), for a period of about 8 hours (overnightwear) causes corneal swelling of about 11%. However, a preferredextended-wear contact lens will produce, after wear of about 24 hours,including normal sleep periods, corneal swelling of less than about 8%,more preferably less than about 6%, and most preferably less than about4%. A preferred extended-wear contact lens will produce, after wear ofabout 7 days, including normal sleep periods, corneal swelling of lessthan about 10%, more preferably less than about 7%, and most preferablyless than about 5%. Thus, the extended-wear lens must have oxypermpolymer in an amount sufficient to produce oxygen diffusion pathwaysfrom the outer surface to the inner surface of the lens which aresufficient to yield the above properties relating to corneal swelling.

Preferably, the extended-wear lens has a continuous phase of oxypermpolymer extending from the outer surface to the inner surface of thelens.

B. Ionoperm Polymerizable Materials

Ionoperm polymerizable materials include a wide range of materials whichmay be polymerized to form a polymer displaying a relatively high iondiffusion rate therethrough. In addition, these materials must berelatively ophthalmically compatible. These ionoperm polymerizablematerials include, without limitation thereto, acrylates andmethacrylates, such as 2-hydroxyethyl methacrylate, acrylamide,methacrylamide, and dimethylacrylamide; poly(alkylene glycols), such aspoly(ethylene glycol); N-vinyl pyrrolidones such asN-vinyl-2-pyrrolidone; and the like and mixtures thereof. Other ionopermmaterials include, without limitation, those disclosed and described inU.S. Pat. No. 5,760,100 issued to Nicolson et al., which is incorporatedherein by reference in its entirety.

C. Weight Ratios

The ratios of oxyperm to ionoperm polymerizable materials may varysubstantially, depending on the selected balance of oxygen permeabilityand ion permeability for the chosen end-use of the molded polymericarticle. Preferably, the volumetric ratio of oxyperm to ionopermmaterial (including water) in the fully hydrated lens is about 40 toabout 60 to about 60 to about 40. However, weight percentages, based onthe total weight of the lens, will be defined because weight percentagesare more conveniently utilized in lens fabrication. Preferably, theextended-wear contact lenses having substantially only ionoperm andoxyperm materials will have about 60 to about 85 weight percent oxypermpolymerizable material and about 15 to about 40 weight percent ionopermpolymerizable material in the prepolymerization mixture, based on totalpolymerizable material weight. More preferably, the prepolymerizationmixture will contain about 70 to about 82 weight percent oxypermpolymerizable material and about 18 to about 30 weight percent ionopermpolymerizable material, based on total polymerizable material weight.

A wide variety of additional polymerizable materials may be included inthe mixture prior to polymerization. Cross-linking agents, such asethylene glycol dimethacrylate (EGDMA), may be added to improvestructural integrity and mechanical strength. Antimicrobialpolymerizable materials such as poly(quatemary ammonium) salts may beadded to inhibit microbial growth on the lens material. Also, additionalionoperm monomers or macromers and/or oxyperm polymerizable materialsmay be added to adjust the oxygen permeability and ion permeability ofthe final molded article.

An especially advantageous polymerizable material is TRIS, which may actboth to increase oxygen permeability and to improve the modulus ofelasticity.

A preferred prepolymerization mixture will include (a) about 20 to 60weight percent oxyperm macromer, (b) about 20 to 40 weight percentionoperm polymerizable material, and (c) about 1 to 35 weight percentTRIS, based on the total lens weight. More preferably, the amount ofTRIS is about 10 to 33 weight percent, based on the totalprepolymerization mixture weight.

In a preferred embodiment, the prepolymerization mixture includes lessthan about 5 weight percent cross-linking agent, based on the totalprepolymerization mixture weight. More preferably, the prepolymerizationmixture includes less than about 2 weight percent cross-linking agent,based on the total prepolymerization mixture weight. Even morepreferably, the prepolymerization mixture includes substantially nocross-linking agent.

The previously described ranges for oxyperm polymerizable materials,ionoperm polymerizable materials, and TRIS are offered to enable thereader to better comprehend the invention. However, it should be notedthat the specific weight or volume percentages of oxyperm and ionopermpolymerizable materials are not the most critical factors to consider inpreparing a good ophthalmic lens. More importantly, the lens must havesufficient ion permeability for good on-eye movement and sufficientoxygen permeability for good corneal health during an extended wearperiod.

D. Oxygen Transmissibility and Permeability

As mentioned earlier, the cornea receives oxygen primarily from thecorneal surface which is exposed to the environment, in contrast toother tissues which receive oxygen from blood flow. Thus, an ophthalmiclens which may be worn on the eye for extended periods of time mustallow sufficient oxygen to permeate through the lens to the cornea tosustain corneal health. One result of the cornea receiving an inadequateamount of oxygen is that the cornea will swell. In a preferredembodiment, the oxygen transmissibility of the present ophthalmic lensesis sufficient to prevent any clinically significant amount of cornealswelling from occurring.

A preferred ophthalmic lens material will have an oxygentransmissibility, Dk/t, of at least 60 (cm³ oxygen)(mm)/mm-cm²×(sec/mmHg)×10⁻⁹ or [barrers/mm], more preferably at least 65 barrers/mm, andmost preferably at least 70-80 barrers/mm. The oxygen permeability of alens and oxygen transmissibility of a lens material may be determined bythe following technique. Oxygen fluxes (J) are measured at 34EC in a wetcell (i.e., gas streams are maintained at about 100% relative humidity)using a Dk1000 instrument (available from Applied Design and DevelopmentCo., Norcross, Ga.), or similar analytical instrument. An air stream,having a known percentage of oxygen (e.g., 21%), is passed across oneside of the lens at a rate of about 10 to 20 cm³/min., while a nitrogenstream is passed on the opposite side of the lens at a rate of about 10to 20 cm³/min. The barometric pressure surrounding the system,P_(measured), is measured. The thickness (t) of the lens in the areabeing exposed for testing is determined by measuring about 10 locationswith a Mitotoya micrometer VL-50, or similar instrument, and averagingthe measurements. The oxygen concentration in the nitrogen stream (i.e.,oxygen which diffuses through the lens) is measured using the DK1000instrument. The oxygen permeability of the lens material, D_(k), isdetermined from the following formula:

D _(k) =Jt/(P _(oxygen))

where J=oxygen flux [microliters O₂/cm²-minute]

P_(oxygen)=(P_(measured)−P_(water) vapor)=(% O₂ in air stream) [mmHg]=partial pressure of oxygen in the air stream

P_(measured)=barometric pressure (mm Hg)

P_(water) vapor=0 mm Hg at 34 C (in a dry cell) (mm Hg)

P_(water) vapor=40 mm Hg at 34 C (in a wet cell) (mm Hg)

t=average thickness of the lens over the exposed test area (mm)

where D_(k) is expressed in units of barrers, i.e., ((ccoxygen)(mm)/cm²)××(sec/mm Hg)××10−10.

The oxygen transmissibility (D_(k)/t) of the material may be calculatedby dividing the oxygen permeability (D_(k)) by the average thickness (t)of the lens.

E. Examples of Suitable Polymeric Lens Materials

Examples of suitable polymeric lens materials include, withoutlimitation thereto, those disclosed and described in U.S. Pat. No.5,760,100 issued to Nicolson et al., U.S. Pat. No. 4,136,250 issued toMueller et al., U.S. Pat. No. 4,153,641 issued to Deichert et al., U.S.Pat. No. 4,605,712 issued to Mueller et al., U.S. Pat. No. 4,711,943issued to Harvey, III, U.S. Pat. No. 5,158,717 issued to Lai, U.S. Pat.No. 5,260,000 issued to Nandu et al., and U.S. Pat. No. 5,346,946 issuedto Yokayama et al., which are all herein incorporated by reference intheir entireties.

Preferably, the polymer matrix comprises a polysiloxane, fluorosiloxano,fluorine-containing monomer, hydrophilic monomer, hydrophobic monomer,or a copolymer thereof, or a mixture thereof.

Preferably, the lens material or formulation comprises at least onemacromer, TRIS, DMA, ethanol and a photoinitiator. More preferably, thelens formulation comprises 25.92%, by weight of the formulation, ofmacromer, 28.88% by weight of the formulation, of DMA, 19.25% by weightof the formulation, of TRIS, 24.95% by weight of the formulation, ofethanol, and 1.00% by weight of the formulation, of a photointiator(DAROCUR, for example).

III. Comonomers

The present invention further relates to a polymer matrix comprising apolymerization product of at least one polymer precursor or macromeraccording to the invention as defined above and, if appropriate, atleast one vinylic comonomer (a).

The preferred composition of a polymer according to the inventioncomprises a weight content, with respect to the total polymer, of amacromer according to the invention in the range from 100 to 0.5%, inparticular in the range from 80 to 10%, and preferably in the range from70 to 30%.

In a preferred embodiment, a polymerization product comprises at leastone macromer according to the invention, a comonomer is absent, and thepolymer is preferably a homopolymer.

A comonomer (a), which is contained in a polymer according to theinvention, can be hydrophilic or hydrophobic or a mixture of both.Suitable comonomers include, in particular, those which are usually usedfor the preparation of contact lenses and biomedical materials. Ahydrophobic comonomer (a) is understood as meaning monomers whichtypically give, as a homopolymer, polymers which are water-insoluble andcan absorb less than 10% by weight of water.

Analogously, a hydrophilic comonomer (a) is understood as meaning amonomer which typically gives, as a homopolymer, a polymer which iswater-soluble or can absorb at least 10% by weight of water.

Suitable hydrophobic comonomers (a) include, but are not limited toC₁-C₁₈ alkyl and C₃-C₁₈ cycloalkyl acrylates and methacrylates, C₃-C₁₈alkylacrylamides and -methacrylamides, acrylonitrile, methacrylonitrile,vinyl C₁-C₁₈ alkanoates, C₂-C₁₈ alkenes, C₂-C₁₈ haloalkenes, styrene,lower alkyl styrene, lower alkyl vinyl ethers, C₂-C₁₀ perfluoroalkylacrylates and methacrylates or correspondingly partly fluorinatedacrylates and methacrylates, C₃-C₁₂perfluoroalkyl-ethyl-thiocarbonylaminoethyl acrylates and methacrylates,acryloxy- and methacryloxy-alkylsiloxanes, -vinylcarbazole and C₁-C₁₂alkyl esters of maleic acid, fumaric acid, itaconic acid, mesaconic acidand the like. Preferred comonomers are, for example, acrylonitrile,C₁-C₄ alkyl esters of vinylically unsaturated carboxylic acids having 3to 5 carbon atoms, or vinyl esters of carboxylic acids having up to 5carbon atoms.

Examples of suitable hydrophobic comonomers (a) include, but are notlimited to methyl acrylate, ethyl acrylate, propyl acrylate, isopropylacrylate, isobutyl acrylate (IBA), isooctyl acrylate (OA), isodecylacrylate (DA), cyclohexyl acrylate, 2-ethylhexyl acrylate (EHA), methylmethacrylate, ethyl methacrylate, propyl methacrylate, butyl acrylate,vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate,styrene, chloroprene, vinyl chloride, vinylidene chloride,acrylonitrile, 1-butene, butadiene, methacrylonitrile, vinyl toluene,vinyl ethyl ether, perfluorohexylethylthiocarbonylaminoethylmethacrylate, isobornyl methacrylate, trifluoroethyl methacrylate,hexafluoroisopropyl methacrylate, hexafluorobutyl (meth)acrylate (HFBMAand HFBA), TRIS, 3-methacryloxypropylpentamethyldisiloxane andbis(methacryloxyalkyl) tetramethyldisiloxane. Preferred examples ofhydrophobic comonomers (a) are methyl methacrylate, IBA, HFBA, HFBMA,OA, EHA, DA, TRIS and acrylonitrile.

Suitable hydrophilic comonomers (a) include, but are not limited tohydroxyl-substituted lower alkyl acrylates and methacrylates,acrylamide, methacrylamide, lower alkylacrylamides and -methacrylamides,ethoxylated acrylates and methacrylates, hydroxyl-substituted loweralkylacrylamides and -methacrylamides, hydroxyl-substituted lower alkylvinyl ethers, sodium vinylsulfonate, sodium styrenesulfonate,2-acrylamido-2-methylpropanesulfonic acid, N-vinylpyrrole,-vinyl-2-pyrrolidone, 2-vinyloxazoline,2-vinyl-4,4′-dialkyloxazolin-5-one, 2- and 4-vinylpyridine, vinylicallyunsaturated carboxylic acids having a total of 3 to 5 carbon atoms,amino-lower alkyl (where the term “amino” also includes quaternaryammonium), mono-lower alkylamino-lower alkyl and di-loweralkylamino-lower alkyl acrylates and methacrylates, allyl alcohol andthe like. Preferred comonomers are, for example, N-vinyl-2-pyrrolidone,acrylamide, methacrylamide, hydroxyl-substituted lower alkyl acrylatesand methacrylates, hydroxyl-substituted lower alkylacrylamides and-methacrylamides and vinylically unsaturated carboxylic acids having atotal of 3 to 5 carbon atoms.

Examples of suitable hydrophilic comonomers (a) include hydroxyethylmethacrylate (HEMA), hydroxyethyl acrylate, hydroxypropyl acrylate,trimethylammonium-2-hydroxypropyl methacrylate hydrochloride (Blemer®QA, for example from Nippon Oil), dimethylaminoethyl meth acrylate(DMAEMA), dimethylaminoethyl methacrylamide, acrylamide, methacrylamide,N,N-dimethylacrylamide (DMA), allyl alcohol, vinylpyridine, glycerolmethacrylate, N-(1,1-dimethyl-3-oxobutyl)acrylamide,-vinyl-2-pyrrolidone (NVP), acrylic acid, methacrylic acid and the like.

Preferred hydrophilic comonomers (a) are 2-hydroxyethyl methacrylate,dimethylaminoethyl methacrylate, trimethylammonium-2-hydroxypropylmethacrylate hydrochloride, and N-vinyl-2-pyrrolidone.

The polymers according to the invention are built up in a manner knownper se from the corresponding monomers and/or macromers according to theinvention by a polymerization reaction with which the expert isfamiliar. Usually, a mixture of the abovementioned monomers is heated,with the addition of an agent which forms free radicals. Such an agentwhich forms free radicals is, for example, azoisobutyronitrile (AIBN),potassium peroxodisulfate, dibenzoyl peroxide, hydrogen peroxide orsodium percarbonate. If the compounds mentioned are heated, for example,free radicals are then formed, by homolysis, and can then, for example,initiate a polymerization.

Polymerization can be carried out in the presence or absence of asolvent. Suitable solvents are in principle all solvents which dissolvethe monomers used, for example water, alcohols, such as lower alkanols,for example ethanol or methanol, and furthermore carboxylic acid amides,such as dimethylformamide, dipolar aprotic solvents, such as dimethylsulfoxide or methyl ethyl ketone, ketones, for example acetone orcyclohexanone, hydrocarbons, for example toluene, ethers, for exampleTHF, dimethoxyethane or dioxane, and halogenated hydrocarbons, forexample trichloroethane, and also mixtures of suitable solvents, forexample mixtures of water with an alcohol, for example a water/ethanolor a water/methanol mixture.

If appropriate, a polymer network can be intensified by addition of aso-called crosslinking agent, for example a polyunsaturated comonomer(b). The invention furthermore relates to a polymer comprising thepolymerization product of a macromer according to the invention with, ifappropriate, at least one vinylic comonomer (a) and with at least onecomonomer (b).

Examples of typical comonomers (b) are, for example,allyl(meth)acrylate, lower alkylene glycol di(meth)acrylate, poly loweralkylene glycol di(meth)acrylate, lower alkylene di(meth)acrylate,divinyl ether, divinyl sulfone, di- or trivinylbenzene,trimethylolpropane tri(meth)acrylate, pentaerythritoltetra(meth)acrylate, bisphenol A di(meth)acrylate,methylenebis(meth)acrylamide, triallyl phthalate or diallyl phthalate.The amount of comonomer (b) used is expressed in the weight content withrespect to the total polymer and is in the range from 20 to 0.05 %, inparticular in the range from 10 to 0.1%, and preferably in the rangefrom 2 to 0.1%.

IV. Organic or Inorganic Pigments

The class of radiation-absorbing additives useful with the presentinvention are organic or inorganic pigments, or derivatives thereof.Useful pigments include, but are not limited to phthalocyanine blue,phthalocyanine green, titanium (iv) oxide, iron oxide red, iron oxideyellow, chromophtal violet and chromophtal oxide green. The use oforganic pigments, particularly phthalocyanine pigments, moreparticularly copper phthalocyanine pigments, and even more particularlycopper phthalocyanine blue pigment (e.g., Color Index Pigment Blue 15,Constitution No. 74160) is preferred.

The amount of pigment necessary in a particular application may varywithin wide limits dependent, in part, upon the desired final productdimensions and desired visible and/or ultraviolet light transmission.For example, an amount of pigment is chosen so that the opticaltransmission of the final molding or lens is, for example, greater than80%, preferably greater than 90%, more preferably from about 92% toabout 99.5%, and most preferably from about 93% to about 97%. The abovetransmission values refer to a 100 μm center thickness of the lens andto the wavelength of the absorption maximum of the respective pigment.The amount of pigment necessary to achieve the optical transmission isadvantageously chosen so that the weight percentage of pigment, based onthe total weight of the polymer precursor, and optional comonomerspresent in the prepolymerization mixture according to step (c), is fromabout 0.0001% to about 0.05%. Preferably, the weight percentage ofpigment is from about 0.0001% to about 0.02%. More preferably, theweight percentage of pigment is from about 0.0001% to about 0.01%.

The particle size of the pigment may vary within wide limits. Ingeneral, the particle size should be small enough to avoid lightscattering, which is clinically significant for the degree of tintintensity required. An average or median particle size (as measured byHORIBA LA-910 particle size analyzer) of less than or equal to about 4μm, preferably less than or equal to about 0.6 μm, more preferably fromabout 0.05 Φm to about 1 μm, and even more preferably from about 0.05 μmto about 0.5 μm has proven advantageous.

In general, the pigment is provided in a dispersion, which comprises thepigment and at least one dispersing agent. It has also been surprisinglyfound that the polymer precursor or lens formulation described abovepromotes dispersion of the pigment particles and may act as a dispersingagent.

V. Dispersing Agents

The pigments outlined above are preferably dispersed in a dispersingagent to form a miscible, liquid colorant dispersion. Typically,pigments do not mix well directly into a lens-forming material. Thepigment agglomerates and forms speckles and disrupts the visualperformance of the resulting lens. Using a dispersing agent overcomesthis problem. The dispersing agent acts to suspend and separate thepigment particles prior to mixing with the lens-forming material.

Examples of suitable dispersing agents include, but are not limited todimethyl acrylamide (DMA), methyl acrylate, ethyl acrylate, propylacrylate, isopropyl acrylate, isobutyl acrylate (IBA), isooctyl acrylate(OA), isodecyl acrylate (DA), cyclohexyl acrylate, 2-ethylhexyl acrylate(EHA), methyl methacrylate, ethyl methacrylate, propyl methacrylate,butyl acrylate, vinyl acetate, vinyl propionate, vinyl butyrate, vinylvalerate, styrene, chloroprene, vinyl chloride, vinylidene chloride,acrylonitrile, 1-butene, butadiene, methacrylonitrile, vinyl toluene,vinyl ethyl ether, perfluorohexylethylthiocarbonylaminoethylmethacrylate, isobornyl methacrylate, trifluoroethyl methacrylate,hexafluoroisopropyl methacrylate, hexafluorobutyl (meth)acrylate (HFBMAand HFBA), HEMA, TRIS, 3-methacryloxypropylpentamethyldisiloxane andbis(methacryloxypropyl) tetramethyldisiloxane, or a mixture thereof.

Also suitable as a dispersing agent is any monomer comprisingalkylenetris(trimethylsiloxy) silane.

The most preferred dispersing agent is TRIS. Since TRIS preferably isalready a significant component of the preferred lens material, thepigment separates and is suspended in the lens material better ifdispersed into TRIS prior to incorporating into the completelens-forming material. The dispersing agent may also be the samematerial as the polymer precursor outlined above.

The pigment amounts of the pigment dispersion employed in this inventionmay vary within wide limits. In general, a pigment comprises from about1 to about 70%, by weight, preferably from about 1 to about 30%, byweight, and more preferably from about 4 to about 10%, by weight, basedon the weight of the entire dispersion.

The pigment dispersion may be prepared, for example, by simply admixingthe pigment and the dispersing agent in a suitable conventional mixingdevice, preferably in an attritor or a microfluidizer. A stock colorantdispersion solution may be also made by first forming a concentrateddispersion of pigment in a dispersing agent and then adding additionaldispersing agent to dilute the concentrated dispersion and create astock colorant dispersion or solution. In some cases, it may beappropriate to filter or centrifuge the pigment dispersion prior tofurther processing it in order to exclude pigment particles having aparticle size that exceeds the aforementioned preferred sizes.

VI. Photoinitiators

A polymerization reaction (photopolymerization or photocrosslinking) canparticularly be carried out using a photoinitiator. Examples ofphotoinitiators are familiar to the expert, and specifically, suitablephotoinitiators include, but are not limited to benzoin methyl ether,1-hydroxycyclohexylphenyl ketone and DAROCUR and IRGACUR types,preferably DAROCUR 1173® and DAROCUR 2959®, available from CibaSpecialty Chemicals (Tarrytown, N.Y.). Reactive photoinitiators whichcan be incorporated, for example, into a macromer or can be used as aspecial comonomer (a) are also suitable. Examples of these are to befound in EP 632 329.

For photopolymerization, a photoinitiator, which can initiate freeradical polymerization and/or crosslinking by the use of light, issuitably added. A reasonable amount of mixing is preferred to distributethe photoinitiator substantially uniformly throughout the polymerprecursor solution. The amount of photoinitiator can be chosen withinwide limits. An amount of up to 0.05 g/g, preferably up to 0.003 g/g, ofpolymer is preferred.

The photopolymerization can be triggered by actinic radiation, forexample light, in particular UV light, of a suitable wavelength. Theradiation source may also be gamma or X-radiation. The spectralrequirements can be controlled accordingly, if appropriate, by additionof suitable photosensitizers.

VII. Ophthalmically Compatible Surfaces

The ophthalmic lenses of the present invention have a surface which isbiocompatible with ocular tissue and ocular fluids during the desiredextended period of contact. In one preferred embodiment, the ophthalmiclenses of the present invention include a core material, as definedabove, surrounded, at least in part, by a surface which is morehydrophilic and lipophobic than the core material. A hydrophilic surfaceis desirable in order to enhance the compatibility of the lens with theocular tissues and tear fluids. As surface hydrophilicity increases,undesirable attraction and adherence of lipids and proteinaceous mattertypically decreases. There are factors other than surfacehydrophilicity, such as immunological response, which may contribute todeposit accumulation on the lens. Deposition of lipids and proteinaceousmatter causes haze on the lens, thereby reducing visual clarity.Proteinaceous deposits may also cause other problems, such as irritationto the eye. After extended periods of continuous or intermittent wear,the lens must be removed from the eye for cleaning, i.e., depositremoval. Therefore, increased surface hydrophilicity, and concomitantreductions in deposits of biological matter, allows increased wear time.

“Surface treatment processes,” as used herein, refers to processes torender a surface more ophthalmically compatible, in which, by means ofcontact with a vapor or liquid, and/or by means of application of anenergy source (1) a coating is applied to the surface of an article, (2)chemical species are adsorbed onto the surface of an article, (3) thechemical nature (e.g., electrostatic charge) of chemical groups on thesurface of an article are altered, or (4) the surface properties of anarticle are otherwise modified.

There are a variety of methods disclosed in the art for rendering asurface of a material hydrophilic. For example, the lens may be coatedwith a layer of a hydrophilic polymeric material. Alternatively,hydrophilic groups may be grafted onto the surface of the lens, therebyproducing a monolayer of hydrophilic material. These coating or graftingprocesses may be effected by a number of processes, including withoutlimitation thereto, exposing the lens to plasma gas or immersing thelens in a monomeric solution under appropriate conditions.

Another set of methods of altering the surface properties of a lensinvolves treatment prior to polymerization to form the lens. Forexample, the mold may be treated with a plasma (i.e., an ionized gas), astatic electrical charge, irradiation, or other energy source, therebycausing the prepolymerization mixture immediately adjacent the moldsurface to differ in composition from the core of the prepolymerizationmixture.

A preferred class of surface treatment processes are plasma processes,in which an ionized gas is applied to the surface of an article. Plasmagases and processing conditions are described more fully in U.S. Pat.Nos. 4,312,575 and 4,632,844, which are incorporated herein byreference. The plasma gas is preferably a mixture of lower alkanes andnitrogen, oxygen or an inert gas.

In a preferred embodiment, the lens is plasma treated in the presence ofa mixture of (a) a C₁₋₆ alkane and (b) a gas selected from the groupconsisting of nitrogen, argon, oxygen, and mixtures thereof. In a morepreferred embodiment, the lens is plasma treated in the presence of amixture of methane and air.

VIII. Utility

A. Ophthalmic Moldings

All the information outlined above naturally apply not only to contactlenses, but also to other moldings according to this invention. Whilevisibility-tinted ophthalmic lenses are the preferred products, thepresent invention may have utility in the fabrication of a wide varietyof translucent or transparent polymeric products, including withoutlimitation thereto, translucent automotive shields or glazing, films ormembranes such as membranes for diffusion control, photostructurizablefilms for information storage or photoresist materials, and plasticeyeglasses or spectacles. Ophthalmic lenses, as used herein, refers tocontact lenses (hard or soft), intraocular lenses and artificialcorneas. The present invention has particular utility regarding thefabrication of soft, tinted high Dk contact lenses, which areedge-to-edge tinted so that the user can identify the lenses in a lenscontaining container.

Examples of other ophthalmic moldings include without limitationthereto, contact lenses for eye color modification, ophthalmic drugdelivery devices, ophthalmic wound healing devices, and the like.

The sum of the various advantageous aspects in the production of themoldings of the invention leads to the moldings of the invention beingsuitable especially as mass-produced articles, for example as contactlenses that are worn for a short period of time and are then replaced bynew lenses, or as “extended wear” contact lenses.

B. Contact Lenses

As described above, the present ophthalmic moldings have special utilityas contact lenses. Contact lenses having sufficient oxygen and watertransmission rates from inner (base curve) to outer (front curve)surface may be continuously worn for longer periods of time withoutsubstantial corneal swelling or wearer discomfort. The method of wearincludes (a) applying the lens to the eye and (b) allowing the lens toremain in intimate contact with the eye and tear fluids for a periodwithout substantial adverse impact on corneal health or wearer comfort.

A preferred method includes additional steps of (c) removing the lensfrom the ocular environment; (d) treating the lens (i.e., disinfectingor cleaning the lens); (e) re-applying the lens to the eye; and (f)allowing the lens to remain in intimate contact with the eye and tearfluids for a period without substantial adverse impact on corneal healthor wearer comfort.

A specific embodiment of the invention is directed to contact lensescomprising a novel, visibly tinted polymer matrix. Such contact lenseshave a range of unusual and extremely advantageous properties. Amongstthese properties are, for example, their excellent compatibility withthe human cornea (if necessary after suitable surface treatment(coating)) and with tear fluid, which is based on a balanced ratiobetween water content and water permeability, oxygen permeability andmechanical and adsorptive properties. This balance of desirableproperties results in high comfort and the absence of irritation andallergenic effects. Owing to their favorable permeability propertieswith respect to various salts, nutrients, water and diverse othercomponents of tear fluid and gases (CO₂ and O₂), the novel contactlenses have no effect, or virtually no effect, on the natural metabolicprocesses in the cornea. In contrast to many other siloxane-containingcontact lenses, the present lenses have chemical and mechanicalproperties and ion permeability sufficient to avoid the undesiredbinding effect. Furthermore, the novel contact lenses have highdimensional stability and shelf life.

The high oxygen permeability is required to prevent corneal swelling,thereby reducing the likelihood of ocular damage and wearer discomfortduring periods of extended wear. High ion permeability enables a lens tomove on the eye such that corneal health is not substantially alteredand wearer comfort is acceptable during a period of extended, continuouscontact with ocular tissue and ocular fluids, if necessary.

Tinting a lens enables the user to easily locate a lens in a clearsolution within a lens storage, disinfecting or cleaning container.Generally, the tinted lenses of this invention are uniformly tintedthroughout the body of the lens. Moreover, the lenses are bleachresistant, and due to a quantitative incorporation of the pigment intothe lens matrix, show no leaching or migration of the pigment out of thelens. In addition, the tinted contact lenses are optically clear andtransparent and have transmission values % T that are equivalent tountinted lenses.

The edge-to-edge tinted contact lenses of this invention can be producedin a very simple and efficient manner as compared with the prior art.This is the result of several factors. First, the starting materials areinexpensive and easy to obtain or prepare. Second, the prepolymers aresurprisingly stable. Accordingly, since it is possible to use a stableprepolymer, and further since the pigment is entrapped quantitativelywithin the resulting polymer matrix during the cross-linking orpolymerization step, virtually no subsequent purification, such as,especially the complex extraction of pigment and/or unpolymerizedcomponents is required (e.g., to meet ophthalmic and regulatoryrequirements). A further significant advantage of the present methodsand compositions is that the pigment does not deactivate during thecross-linking or polymerization step. It has been unexpectedly foundthat pigments, particularly metal (e.g., copper) phthalocyanine pigmentsand equivalents thereof, are not subject to any substantial tintingdeactivation during the application of UV radiation to form the contactlens. In contrast, quite a large number of dyes are subject to bleachingduring the polymerization or molding step of the lens making process.

Lastly, the preferred contact lenses of the present invention are thosewhich are comfortable over the period of wear. If the lens diameter istoo small, the eyelids will not cover any portion of the lens when theeye is open. Thus, the eyelids will contact the edge of the lens eachtime the eyelid is closed. This repeated eyelid-lens interactiontypically causes irritation, wearer discomfort, and lens dislodgement.Accordingly, the preferred contact lens diameters are those which aresufficiently large to minimize eyelid-lens interaction and theassociated irritation. Preferably, the contact lens has a diameter ofabout 12 to about 16 mm, more preferably about 13 to 15 mm, and mostpreferably about 13.5 to 14.8 mm.

IX. Methods of Manufacture

The tinted, high Dk ophthalmic molding or lens of this invention may bemanufactured, generally, by thoroughly mixing the polymerizablematerials including the polymer precursor (and any comonomers) and thepigment dispersion, applying an appropriate amount of the mixture to alens mold cavity, and initiating polymerization. Photoinitiators, suchas those commercially available photoinitiators disclosed above, may beadded to the prepolymerization mixture (polymer precursor and pigmentdispersion) to aid in initiating polymerization. Polymerization may beinitiated by a number of well known techniques, which, depending on thepolymerizable material, may include application of radiation such asmicrowave, thermal, e-beam and ultraviolet. A preferred method ofinitiating polymerization is by application of ultraviolet radiation.For the introduction of the prepolymerization mixture into a mold,processes known per se can be used, such as, especially, conventionalmetering in, for example, by means of dropwise introduction.

Appropriate molds or mold halves may be manufactured from disposable orrecyclable polymeric materials (e.g., polypropylene or polystyrene)which transmit radiation of the chosen wavelength sufficient tocross-link or polymerize the polymer precursor. Alternatively, reusablemolds may be manufactured from materials such as quartz, sapphire ormetals.

When the moldings to be produced are contact lenses, they can beproduced in a manner known per se, for example, in a conventional“spin-casting” mold, as described, for example in U.S. Pat. No.3,408,429. However, double-sided molding (DSM) processes, such asdescribed in U.S. Pat. No. 4,347,198, which is incorporated byreference, are preferred. Double-sided molding processes typicallyutilize a concave (also known as a “female” or “front surface”) moldhalf which mates with a convex (also known as a “male” or “backsurface”) mold half. Typically, in the DSM process, liquid monomer orpolymer precursor mixture is dispensed into the female mold half, themale mold half is affixed to the female mold half, and light (e.g., UV)is applied to initiate polymerization or cross-linking and form a solidlens.

It is to be emphasized that, according to the invention, thepolymerization or cross-linking can be effected in a very short time,for example, in less than 60 minutes, preferably less than 20 minutes,more preferably less than 5 minutes and most preferably in less than 30seconds. Opening the mold to remove the resulting molding can be carriedout in a manner known per se.

It has been discovered that the ion and/or water permeability of some ofthe aforementioned core materials may be increased by initiating andcompleting polymerization in an atmosphere which is substantially freeof oxygen. Suitable gases which are readily commercially availableinclude, without limitation thereto, nitrogen and carbon dioxide. Thus,in a preferred embodiment, the oxyperm and ionoperm polymerizablematerials are polymerized in an atmosphere having less than about 10000ppm oxygen. More preferably, the atmosphere surrounding thepolymerizable material contains less than about 1000 ppm oxygen. Evenmore preferably, the surrounding atmosphere contains less than about 100ppm oxygen, while the most preferred oxygen content is less than about20 ppm.

In the aforementioned embodiment, the prepolymer mixture must bedegassed prior to polymerization. The degassing may be accomplished by anumber of techniques known in the art. One technique for degassing theprepolymer mixture involves the use of a series of freezing and thawingsteps which are repeated until the appropriate gas concentration levelis achieved in the prepolymer mixture. This freeze/thaw method involvescooling the prepolymer mixture until the mixture solidifies, applying avacuum to the solidified prepolymer mixture, discontinuing the vacuum,and thawing the prepolymer mixture until the mixture is again in liquidform. While this degassing technique is advantageous in a laboratorysetting, other degassing techniques known in the art may be moreadvantageous for commercial lens manufacturing processes.

Alternatively, the atmosphere surrounding the lens mold may includeoxygen, under certain conditions. For example, if the lens mold halvesseal adequately to one another and the lens mold material has a low rateof oxygen permeability (e.g., polypropylene), it is possible topolymerize a degassed prepolymer mixture in a mold surrounded by ambientair without reaching prepolymer oxygen concentrations sufficiently highto substantially reduce ion or water permeability of the final lens.Thus, in another preferred embodiment of double-sided molding, the lensis formed by the following steps: (1) the prepolymer mixture isdegassed, (2) a lens mold half is filled with the prepolymer mixture,(3) the mold halves are sealed to one another, and (4) thepolymerization is initiated to form the lens, where the lens mold halvesare formed from a material having a low oxygen permeability and steps(2)-(4) may occur in the presence or absence of oxygen. In thisembodiment, it is preferred that the lens molds are stored in an inertsubstantially oxygen-free atmosphere, e.g., nitrogen or carbon dioxide,prior to use.

When the molding produced according to this invention is a contact lensand when the latter has been produced from a prepolymerization mixturecomprising purified components, then the polymerized or cross-linkedproduct does not contain troublesome impurities. Subsequent extractionis therefore unnecessary.

X. EXAMPLES

The previous disclosure will enable one having ordinary skill in the artto practice the invention. In order to better enable the reader tounderstand specific embodiments and the advantages thereof, reference tothe following examples is suggested. However, the following examplesshould not be read to limit the scope of the invention in any way. Ofthe following, Examples 1A-1D are arranged in accordance with thematerials disclosed and described in U.S. Pat. No. 5,760,100 issued toNicolson et al., which is herein incorporated by reference in itsentirety.

Thus, Examples 1A(i) and 1A(ii) relate to Material “A” as that disclosedand described in U.S. Pat. No. 5,760,100 issued to Nicolson et al.Example 1B relates to Material “B” as that disclosed and described inU.S. Pat. No. 5,760,100 issued to Nicolson et al. Example 1C relates toMaterial “C” as that disclosed and described in U.S. Pat. No. 5,760,100issued to Nicolson et al. Example 1D relates to Material “D” as thatdisclosed and described in U.S. Pat. No. 5,760,100 issued to Nicolson etal. The remaining Examples are not specifically disclosed and describedin U.S. Pat. No. 5,760,100 issued to Nicolson et al. For all thefollowing Examples, temperatures are stated in degrees Celsius (EC),unless otherwise specified.

Example 1A(i)

A polysiloxane macromer is prepared by reacting, at room temperature(about 21° C.), one mole equivalent (about 100 grams) ofpoly(dimethylsiloxane) dialkanol (Shin Etsu Chemical Co., Tokyo, Japan)having hydroxyethyl propoxy end groups with 2 mole equivalents (about21.2 grams) of isophorone diisocyanate (Aldrich Chemical Co., Milwaukee,Wis.) in the presence of about 0.2 grams dibutyltin dilaurate catalyst(Pfaltz & Bauer, Inc., Waterbury, Conn.). After about 48 hours reactiontime, 2.02 mole equivalents (about 38.7 grams) of poly(ethylene glycol)(“PEG”, about 610 g/mol Mn, Dow Chemical Corp., Midland, Mich.) andabout 0.17 grams of dibutyltin dilaurate (about 0.43% by weight PEG) areadded to 80 grams of the reaction product from the prior step.Sufficient chloroform (Aldrich Chemical Co.) is added to the mixture tomake the mixture homogeneous. This mixture is stirred at roomtemperature for about 15 hours. Next, the mixture is stirred for about 8hours at a temperature of about 44 to 48° C., with the temperature heldsubstantially constant by a surrounding oil bath. The chloroform is thenevaporated, in order to achieve a final concentration of about 50% byweight solids, by stirring the mixture at room temperature for about 8hours. Then, about 2.14 mole equivalents (about 10.4 grams) ofisocyanatoethyl methacrylate (“IEM”, Monomer Polymer, Inc.,Feasterville, Pa.) is added to the mixture. Finally, the mixture iscovered with aluminum foil and stirred at room temperature for about 17hours, yielding a polysiloxane-containing macromer having anumber-average molecular weight (Mn) of about 4000 grams per mole.

Example 1A(ii)

A polysiloxane macromer is prepared substantially in accordance with theprocedure described in Example 1A(i).

A copolymer precursor solution is prepared by mixing about 180 gramspolysiloxane-containing macromer, about 15 grams3-methacryloxypropyltris (trimethylsiloxy) silane (Shin Etsu), about 4grams 2-hydroxyethyl methacrylate (“HEMA”, about one gram ethyleneglycol dimethacrylate (“EDGMA”, and about one gram DAROCUR® 1173photoinitiator at room temperature for about 16 hours. The copolymerprecursor solution is then polymerized to form contact lenses.Polypropylene contact lens molds are filled with the copolymer precursorsolution. Ultraviolet light (about 300 to 400 nm) at about 3-6 mW/cm² isapplied to the solution in the mold for about 3 hours at roomtemperature. The UV light causes polymerization, thereby allowing thesolution to form contact lens having the shape of the mold. The lens areextracted with isopropanol to remove remaining chloroform solvent andany unreacted components. A preferred resulting polymer contains about81.8 weight percent polysiloxane macromer, about 13.6% TRIS, about 3.6%2-hydroxyethyl methacrylate, and about 0.9% EDGMA.

Example 1B

51.5 g (50 mmol) of the perfluoropolyether Fomblin® ZDOL (from AusimontS.p.A, Milan) having a mean molecular weight of 1030 g/mol andcontaining 1.96 meq/g of hydroxyl groups according to end-grouptitration is introduced into a three-neck flask together with 50 mg ofdibutyltin dilaurate. The flask contents are evacuated to about 20 mbarwith stirring and subsequently decompressed with argon. This operationis repeated twice. 22.2 g (0.1 mol) of freshly distilled isophoronediisocyanate kept under argon are subsequently added in a counterstreamof argon. The temperature in the flask is kept below 30° C. by coolingwith a water bath. After stirring overnight at room temperature, thereaction is complete. Isocyanate titration gives an NCO content of 1.40meq/g (theory: 1.35 meq/g). 202. of the α,ω-hydroxypropyl-terminatedpolydimethylsiloxane KF-6001 from Shin-Etsu having a mean molecularweight of 2000 g/mol (1.00 meq/g of hydroxyl groups according totitration) are introduced into a flask. The flask contents are evacuatedto approx. 0.1 mbar and decompressed with argon. This operation isrepeated twice. The degassed siloxane is dissolved in 202 ml of freshlydistilled toluene kept under argon, and 100 mg of dibutyltin dilaurate(DBTDL) are added. After complete homogenization of the solution, allthe perfluoropolyether reacted with isophorone diisocyanate (IPDI) isadded under argon. After stirring overnight at room temperature, thereaction is complete. The solvent is stripped off under a high vacuum atroom temperature. Microtitration shows 0.36 meq/g of hydroxyl groups(theory 0.37 meq/g). 13.78 g (88.9 mmol) of 2-isocyanatoethylmethacrylate (IEM) are added under argon to 247 g of theα,ω-hydroxypropyl-terminatedpolysiloxane-perfluoropolyether-polysiloxane three-block copolymer (athree-block copolymer on stoichiometric average, but other block lengthsare also present). The mixture is stirred at room temperature for threedays. Microtitration then no longer shows any isocyanate groups(detection limit 0.01 meq/g). 0.34 meq/g of methacryl groups are found(theory 0.34 meq/g).

The macromer prepared in this way is completely colorless and clear. Itcan be stored in air at room temperature for several months in theabsence of light without any change in molecular weight.

Example 1C

Reaction of α,ω-bis-aminopropyl-dimethylpolysiloxane with D(+)gluconicacid d-lactone: Before the reaction, the amino-functionalizedpolydimethylsiloxane employed for the synthesis (X-22-161-C, Shin Etsu,JP) was finely dispersed in acetonitrile, extracted and then subjectedto molecular distillation.

The following reactions take place with exclusion of H₂ 0.200 g ofpurified amino-functionalized polydimethylsiloxane (0.375 meq of NH₂/g;Mn(VPO) 3400-3900 (VPO, Vapour Pressure Osmometry)), dissolved in 200 mlof absolute THF, are slowly added dropwise to a suspension of 13.35 g(75 mmol) of D(+)gluconic acid d-lactone in 50 ml of absolute THF andthe mixture is stirred at 40° C. for about 24 hours until the lactonehas reacted completely. (Monitoring of the reaction by thin layerchromatography (TLC): silica gel; i-propanol/H2O ethyl acetate 6:3:1;staining with Ce(IV) sulfate/phosphoromolybdic acid solution (CPSreagent)). After the reaction, the reaction solution is concentrated todryness and the residue is dried under 3 Pa (0.03 mbar) for 48 hours.213.3 g of α,ω-bis(3-gluconamidopropyl)-poly-dimethylsiloxane areobtained. Titration of the amino groups with perchloric acid shows aconversion of the amino groups of more than 99.8%.

Example 1D

In a dry box under nitrogen atmosphere, about 200 grams of dry PDMSdipropoxyethanol (Shin-Etsu) is added to a container. Isocyanatoethylmethacrylate (IEM) in an amount equal to about 2 moles per mole PDMSdialkanol is added to the container. About 0.1 weight percent dibutyltindilaurate (DBTL) catalyst, based on PDMS dialkanol weight, is added tothe container along with a stir bar. The container is immersed in an oilbath atop a stir plate, and secured in place with a clamp. A stream ofUPC air at about 2 psig is passed over the mixture. The mixture isagitated at room temperature (about 22° C.) for about 24 hours. Aniterative procedure follows in which the mixture is analyzed forisocyanate content and IEM is added if the PDMS dialkoxyalkanol has notbeen completely reacted. The mixture is stirred about 24 hours more. Themacromer produced is a siloxane-containing macromer.

Example 2

(Preparation of a Pigment Dispersion)

The following example illustrates the preparation of a dispersion of ablue pigment, copper phthalocyanine, in a organosiloxane monomer,Shin-Etsu KF2801, or TRIS, according to an embodiment of this invention.This dispersion is used in contact lens formulations. Since theseproducts are FDA approved and controlled, the dispersion must beprepared with thoroughly cleaned equipment according to GMP methods andconditions.

500 g of a suspension of 5% copper phthalocyanine (CuP) is dispersed inTRIS. A dispersion is prepared using the M-110EH microfluidizer equippedwith an H30Z (#6366)/G10Z (#6107) chamber set. The process time is 60minutes, the process pressure is 25,000 psi. The process temperature iskept at # 30EC. A mechanical stirrer is set up so that the recirculatingdispersion can be stirred in the liquid reservoir throughout thedispersion process.

The microfluidizer is first flushed with ethanol, then thoroughly primedwith pure TRIS prior to the process. A 5% suspension of CuP/TRIS ispoured into the reservoir and stirred. Flow through the M-110EH isstarted. Recirculation of the dispersion into the reservoir is startedonly after several ml of blue dispersion is expelled from the exit line.After one hour of recirculation, the machine is stopped, and all of thedispersion is collected from the sample reservoir. The void volumeremaining in the machine is discarded, as one flushes the machine withpure TRIS, then ethanol, to rinse and clean the machine.

A mean particle size of approximately −0.35 μm, with >80% of theparticles smaller than 0.45 μm , and all the particles <2 μm in size isachieved. The yield of dispersion is approximately 80%. Particle size isanalyzed on a HORIBA LA-910 or 920, using ethanol as the solvent, withsonication for 3 minutes prior to measurement. Preferably, particle-sizeis measured before and after sonication.

Example 3

(Preparation of a Tinted Prepolymerization Mixture)

Using 100% of a lens formulation of the present invention, the component% s (converted to grams (g)) are as follows:

24.95% ethanol = 24.95 g 28.88% DMA = 28.88 g 19.25% TRIS = 19.25 g25.92% Macromer = 25.92 g  1.00% DAROCUR =  1.00 g 100.00%  = 100.00 g 

The final lens formulation preferably has 50 ppm copper phthalocyanine(CuP) to achieve a preferred tint. The final formulation contains 19.25%TRIS. To calculate the desired 50 ppm in the final lens formulation,divide 50 ppm by 0.1925, which equals 259.74 ppm, or −260 ppm. Thismeans that for every 19.25 g of blue-tinted TRIS (TRIS-blue) that youadd to the lens formulation, it should contain 260 ppm copperphthalocyanine.

260 ppm of blue-tinted TRIS for a lens material may be made by addingthe 5% stock solution of the TRIS-blue to clear TRIS. 5% means 0.05 gcopper phthalocyanine per g of TRIS-blue. Take 1.000000 g as 1 millionparts (adding enough zeros to represent 1,000,000). Then a 5% solutionmeans there are 0.050000 g of copper phthalocyanine per gram of stockTRIS-blue solution, or 50,000 ppm. 50,000 ppm TRIS-blue stock is dilutedto get 260 ppm blue tinted TRIS for the formulation.

Throughout this application, various publications are referenced. Thedisclosures of these publications in their entireties are herebyincorporated by reference into this application in order to more fullydescribe the state of the art to which this invention pertains.

The invention has been clearly described in detail, with particularreference to certain preferred embodiments, in order to enable thereader to practice the invention without undue experimentation. Theoriesof operation have been offered to better enable the reader to understandthe invention, but such theories do not limit the scope of theinvention. In addition, a person having ordinary skill in the art willreadily recognize that many of the previous components, compositions,and parameters may be varied or modified to a reasonable extent withoutdeparting from the scope and spirit of the invention.

Furthermore, titles, headings, example materials or the like areprovided to enhance the reader's comprehension of this document, andshould not be read as limiting the scope of the present invention.Accordingly, the invention is defined by the following claims, andreasonable extensions and equivalents thereof.

What is claimed is:
 1. A soft, tinted ophthalmic molding having anoxygen transmissibility (Dk/t) of at least 60 barrers/mm and comprising:(i) a polymer matrix which is a polymerization product of aprepolymerization mixture having about 60 to 85 weight percent ofoxyperm polymerizable material and about 15 to 40 weight percent ofionoperm polymerizable material; and incorporated therein (ii) particlesof a pigment.
 2. The soft, tinted ophthalmic molding of claim 1, whereinthe polymer matrix is a core material and is at least in part surroundedby an ophthalmically compatible surface obtained by a surface treatmentprocess.
 3. The soft, tinted ophthalmic molding of claim 1, wherein theophthalmic molding is selected from the group consisting of a contactlens for vision correction, a contact lens for eye color modification,an ophthalmic drug delivery device and an ophthalmic wound healingdevice.
 4. The soft, tinted ophthalmic molding of claim 1, wherein theophthalmic molding is a vision correction contact lens.
 5. The soft,tinted ophthalmic molding of claim 1, wherein the oxyperm polymerizablematerial comprises polysiloxane-containing macromer and containingmonomer.
 6. The soft, tinted ophthalmic molding of claim 1, wherein thepigment comprises an organic pigment, an inorganic pigment, or a mixturethereof.
 7. The soft, tinted ophthalmic molding of claim 1, wherein thepigment is a phthalocyanine pigment.
 8. The soft, tinted ophthalmicmolding of claim 7, wherein the pigment is copper phthalocyanine blue.9. A method for making a soft, tinted ophthalmic molding comprising: (a)providing a polymer precursor capable of forming a polymer or copolymerhaving high oxygen permeability, wherein the polymer precursor comprisesabout 60 to 85 weight percent of oxyperm polymerizable material andabout 15 to 40 weight percent of ionoperm polymerizable material; (b)providing a pigment dispersion comprising particles of a pigment and adispersing agent; (c) mixing the pigment dispersion and the polymerprecursor to form a tinted prepolymer mixture; (d) dispensing the tintedprepolymer mixture into a mold; and (e) cross-linking or polymerizingthe tinted prepolymer mixture in the mold to form a soft, tintedophthalmic molding having an oxygen transmissibility (Dk/t) of at least60 barrers/mm and comprising a polymer matrix and the particles of thepigment entrapped therein.
 10. The method of claim 9, wherein the soft,tinted ophthalmic molding is a vision correction contact lens.
 11. Themethod of claim 9, wherein the polymer precursor is a liquid material.12. The method of claim 9, wherein the oxyperm polymerizable materialcomprises a silicone-containing macromer or monomer, afluorine-containing macromer or monomer, or a mixture thereof.
 13. Themethod of claim 9, wherein the oxyperm polymerizable material comprisesa siloxane-containing macromer having a dialkyl siloxane group.
 14. Themethod of claim 9, wherein the pigment dispersion is miscible with thepolymer precursor.
 15. The method of claim 9, wherein the pigmentcomprises an organic pigment, an inorganic pigment, or a mixturethereof.
 16. The method of claim 9, wherein the pigment is aphthalocyanine pigment.
 17. The method of claim 9, wherein thedispersing agent is same material as the polymer precursor of step (a).18. The method of claim 9, wherein the dispersing agent is an acrylatedor methacrylated siloxane monomer.
 19. The method of claim 9, whereinthe dispersing agent is any monomer comprisingalkylenetris(trimethylsiloxy) silane.
 20. The method of claim 9, whereinthe dispersing agent is selected from the group consisting of methylmethacrylate, isobutyl acrylate, isooctyl acrylate, isodecyl acrylate,2-ethylhexyl acrylate, hexafluorobutyl (meth)acrylate, HEMA, TRIS,acrylonitrile, and mixtures thereof.
 21. The method of claim 9, whereinthe weight percentage of the particles of the pigment, based on thetotal weight of the prepolymer mixture, is from greater than zero toabout 0.05 weight percent.
 22. The method of claim 9, wherein step (e)occurs in less than about 5 minutes.
 23. A soft, tinted ophthalmicmolding made by the method of claim
 9. 24. A soft, tinted ophthalmiclens having an oxygen transmissibility (Dk/t) of at least 60 barrers/mmand comprising the reaction product of: (i) a prepolymerization mixturehaving about 60 to 85 weight percent of oxyperm polymerizable materialand about 15 to 40 weight percent of ionoperm polymerizable material,wherein the oxyperm polymerizable material includes asiloxane-containing macromer; and (ii) a pigment dispersion comprisingparticles of a pigment and a dispersing agent.
 25. The soft, tintedophthalmic lens of claim 24, wherein the dispersing agent iscross-linkable or polymerizable with component (i).
 26. The soft, tintedophthalmic lens of claim 24, wherein the siloxane-containing macromerhas a dialkyl siloxane group.
 27. The soft, tinted ophthalmic lens ofclaim 24, wherein the dispersing agent is selected from the groupconsisting of methyl methacrylate, isobutyl acrylate, isooctyl acrylate,isodecyl acrylate, 2-ethylhexyl acrylate, hexafluorobutyl(meth)acrylate, HEMA, TRIS and acrylonitrile, or a mixture thereof. 28.The soft, tinted ophthalmic lens of claim 26, wherein the dispersingagent is TRIS.
 29. A composition for making a soft, tinted ophthalmiclens comprising: (i) about 60 to 85 weight percent of an oxypermpolymerizable material including a siloxane-containing macromer; and(ii) about 15 to 40 weight percent of ionoperm polymerizable material:and (iii) a pigment dispersion comprising particles of a pigment and adispersing agent which is a monomer comprisingalkylenetris(trimethylsiloxy) silane.
 30. The composition of claim 29,wherein the dispersing agent is TRIS.